This study analyzed the influence of different ammonia stripping parameters on ammonia removal efficiency and mass transfer rate. Ammonia stripping was performed on two devices, a column and a packed tower, with artificial ammonium hydroxide wastewater. First, ammonia concentration and pH were varied in a column without liquid circulation. At the same pH, the removal efficiency and mass transfer rate were constant, irrespective of initial ammonia concentration. When pH was increased, the ammonia fraction also increased, resulting in higher removal efficiency and mass transfer rate. Second, the effects of stripping were assessed using a packed tower with fluid circulation. The ammonium hydroxide concentration did not affect the removal efficiency or mass transfer rate. Furthermore, at apparatus liquid-gas ratios of 26.8–107.2 L/m³, a lower liquid-gas ratio led to increased ammonia removal efficiency and mass transfer rate. Conversely, the lower the liquid-gas ratio, the greater the air consumption. In conclusion, considering the removal rate and volume of air supply, the range of optimal liquid-gas ratio was determined as 26.8–53.6 L/m³. In particular, the 26.8 L/m³ condition achieved the best ammonia removal rate of 63.0% through only 6 h of stripping at 70 °C and pH 8.5.

The influence of adsorbate (D2EPHA and kerosene) on the process of zinc electrowinning from sulfuric acid electrolytes was analyzed. The main objective was to critically compare three factors: (1) Three types of activated carbon (AC); (2) adsorption temperatures and contact time; and (3) zinc recovery efficiency. The results showed that organic components reduced the efficiency of zinc recovery. Moreover, wood-based ACs had a higher adsorption capacity than coal- and coconut-based ACs. To maintain a removal efficiency of 99% or more, wood-based ACs should constitute at least 60% of the adsorbate. The temperature of adsorption did not affect the removal efficiency. Additionally, the feeding rate of adsorbate in the solvent was inversely proportional to the removal efficiency. A feeding rate of the liquid pump of over 3 mL/min rapidly increased the delta pressure. For the same contact time, 99% of adsorbate removal occurred at 1 mL/min compared to approximately 97% at 0.5 mL/min. In the presence of 100 mg/L zinc, with increasing adsorbate from 0–5%, the recovery efficiency of zinc decreased from 100% to 0% and the energy consumption increased from 0.0017–0.003 kwh/kg zinc. Considering the energy consumption and zinc deposit mass, 0.1% of the adsorbate is recommended for zinc electrowinning.

The use of coagulants, such as ferric chloride hexahydrate, in wastewater treatment processes is known to induce pipe corrosion and to contribute to the discoloration of treated water. This study explores alternative approaches to sludge dewatering by evaluating the effectiveness of polymeric aluminum chloride (PAC) as a coagulant and polyoxyethylene alkyl ether (POAE) as a surfactant. The impacts of coagulation/flocculation were assessed using time to filtration (TTF) and a pressure filter press. The effects of certain coagulant and surfactant dosages were studied. The inputs were in the range of 105–1750 mg/L for PAC and 28–152 mg/L for POAE, which were determined based on zeta potential (ZP) measurements. The optimal concentrations were 876 mg/L for PAC and 114 mg/L for POAE, resulting in a TTF of less than 1 min. Moreover, the effect of pH on anaerobic sludge dewaterability was investigated. At a low pH below 8, the ZP reached the maximum value, and a higher pH resulted in a reduction in ZP. Under low-pH adjustments, it was observed that the dewatering performance of the POAE surfactant improved more significantly than that of the PAC coagulant. In addition, the effect of pressure was analyzed using a pressure filter under conditions favoring POAE, with relatively lower dosages and greater cost-effectiveness. In order to evaluate the solubility of organic matter under pressurized conditions, the filtrate’s removal efficiency, chemical oxygen demand (COD), and total phosphorus (TP) were investigated. Solubilization did not occur at an increased pressure of around 10 bars. The findings presented in this study provide technical assistance for sludge treatment.

In this study, ultrasonic excitation was employed for filter cloth cleaning, with the aim of predicting optimal cleaning conditions and monitoring the efficiency and performance of the cloth under various cleaning parameters. A clogged filter cloth of uniform size (Φ0.11 m) was secured in a prepared cleaning apparatus, and cleaning experiments were conducted by varying the following operational conditions: time (2, 5, 10 min), frequency (34, 76, 120 kHz), and power output (100, 200, 300 W). Through these experiments, this study sought to investigate the cleaning capacity and efficiency of each condition and to evaluate the effectiveness of ultrasonic cleaning. The morphology of the filter cloths before and after cleaning was examined through SEM imaging, and the weight content of the filter cloths was measured before and after the cleaning experiments to incorporate these values into the cleaning efficiency assessment. Additionally, air permeability measurements were taken to predict the impact of permeability on cleaning performance, which was statistically analyzed based on a predictive model’s equation. The experimental results showed that the maximum recovery rate of air permeability for clogged filter cloths was approximately 28.6%. Using Response Surface Methodology (RSM), the air permeability recovery rate and weight reduction rate were 19.8% and 5.8%, respectively, under conditions of 5.2 min, 34 kHz, and 300 W. It is anticipated that the utilization of the filter press cleaning device will enable data acquisition through repeated experiments and that this device can be used in filter cloth management and operational techniques.